The present invention relates to a dye composition, in particular a lightening dye composition, for keratin fibers, and in particular human keratin fibers, comprising at least one direct dye chosen from the group formed by dyes containing an optionally delocalizable quaternized nitrogen atom and a xe2x80x94Zxe2x95x90Nxe2x80x94 bond, in which Z denotes a nitrogen atom or a xe2x80x94CHxe2x80x94 radical. The invention also relates to the use of such a composition in the above-mentioned application.
It is known to dye keratin fibers, and in particular human hair, with dye compositions containing direct dyes according to a so-called xe2x80x9cdirect dyeingxe2x80x9d process. This process involves applying to the keratin fibers dye molecules that have an affinity for the fibers, leaving the fibres to stand, and then rinsing the fibers. This process allows shading of the color of the keratin fibers to be obtained. It is also known to dye keratin fibers, and in particular human hair, with dye compositions containing oxidation dye precursors (ortho- or para-phenylenediamines and ortho- or para-aminophenols, generally referred to as xe2x80x9coxidation basesxe2x80x9d) and couplers (meta-phenylenediamines, meta-aminophenols and meta-diphenols, also referred to as color modifiers, which allow the xe2x80x9cbasexe2x80x9d colors obtained by the condensation products of the oxidation bases to be modified and enriched with glints), according to a so-called xe2x80x9coxidation dyeingxe2x80x9d process.
The oxidation dyeing process usually involves lightening, that is to say that it involves applying to the keratin fibers, at basic pH, a mixture of bases and couplers and aqueous hydrogen peroxide solution, leaving the applied mixture to stand on the hair and then rinsing the hair. It allows, particularly in the case of hair dyeing, the melanin to be lightened and the hair to be dyed.
Lightening the melanin has the advantageous effect of creating a unified coloration in the case of grey hair, and, in the case of naturally pigmented hair, of bringing out the color, that is to say of making it more visible.
An oxidizing agent and, in particular, an aqueous hydrogen peroxide solution, and a basifying agent are used to obtain this lightening. A lightening of the melanin ranging from xc2xe of a tone to more than 2 tones can be brought about as a function of the concentrations of aqueous hydrogen peroxide and of basifying agent, and also as a function of the nature of the basifying agent. In the case of gentle lightenings, the desired lightening is obtained in the course of superpositions.
In the so-called oxidation dyeing of hair, the use of oxidation bases sometimes leads to problems of sensitization of the scalp. In this case, if it is nevertheless desired to dye the hair, it is then possible only to use direct dyeing, with its drawbacks, in particular that of no longer obtaining the tinting effects of oxidation dyeing since conventional direct dyeing is, by itself, not lightening.
It has already been attempted in the past to obtain lightening dyes, by replacing the oxidation bases and the couplers with direct dyes. However, all the results obtained were less than optimal.
Accordingly, it was proposed to dye the hair with dye compositions based on nitro direct dyes and/or dispersed azo dyes and ammoniacal aqueous hydrogen peroxide (see in this respect French patent no. FR-1,584,965 and Japanese patent no. JP-062,711,435) by applying to the hair a mixture of the dyes and the oxidizing agent, which is prepared just before use. However, the colorations obtained did not prove to be sufficiently fast and disappeared on shampooing, allowing the lightening of the hair fibre to emerge. Such a coloration becomes aesthetically unpleasant by changing over time.
It has also been proposed to dye the hair with compositions based on cationic direct dyes of oxazine type and ammoniacal aqueous hydrogen peroxide (see in this respect Japanese patents JP-53 95693 and JP-55 022638) by applying to the hair, in a first step, ammoniacal aqueous hydrogen peroxide, and then, in a second step, a composition based on the oxazine direct dye. The coloration obtained is not satisfactory, on account of the fact that it requires a process which is made too slow by the standing times of the two successive steps. If, moreover, a mixture, prepared at the time of use, of the oxazine direct dye with ammoniacal aqueous hydrogen peroxide is applied to the hair, the hair fibre is not dyed or, at best, a coloration which is virtually nonexistent is obtained.
Moreover, the Inventor has performed tests to dye the hair with dye compositions based on anionic sulfonic dyes (which are themselves reputed for the excellent fastness) and on ammoniacal aqueous hydrogen peroxide, by applying to the hair a mixture of the dyes and the oxidizing agent, which is prepared just before use. However, in this case, no coloration of the hair fibre was observed.
Now, after considerable research has been conducted in this direction, the Inventor has discovered that it is possible to obtain dyes, in particular lightening dyes, with specific and suitably selected direct dyes, which are fast, homogenous and do not change on washing, by using a mixture which is prepared at the time of use, at basic pH, of an oxidizing agent and at least one direct dye which is chosen from those containing both an optionally delocalizable quaternized nitrogen atom and a xe2x80x94Zxe2x95x90Nxe2x80x94 bond, in which Z denotes a nitrogen atom or a xe2x80x94CHxe2x80x94 radical. This discovery forms the basis of the present invention.
One subject of the present invention is thus a dye composition, in particular a lightening dye composition, for keratin fibers, and in particular for human keratin fibers such as the hair, of the type comprising, in a medium which is suitable for dyeing, at least one direct dye to be mixed at the time or use, at basic pH, with an oxidizing composition, and which is characterized in that it has a basic pH and in that it contains, as the direct dye, at least one dye containing an optionally delocalizable quaternized nitrogen atom and a xe2x80x94Zxe2x95x90Nxe2x80x94 bond in which Z denotes a nitrogen atom or a xe2x80x94CHxe2x80x94 radical.
The dyes used in accordance with the present invention make it possible to achieve homogenous and fast colorations which remain aesthetic over time, since they do not change either over time or on washing. They are furthermore produced very rapidly, and in particular in a standing time of the dye/oxidizing agent mixture of five minutes. In addition, they communicate an especially shiny appearance and a natural feel without overloading, in particular on hair fibers.
Another subject of the present invention relates to a process for dyeing, and in particular lightening, keratin fibers, in particular human keratin fibers such as the hair, which involves applying to those fibers at least one composition (A) containing, in a medium which is suitable for dyeing, at least one direct dye containing an optionally delocalizable quaternized nitrogen atom and a xe2x80x94Zxe2x95x90Nxe2x80x94 bond in which Z denotes a nitrogen atom or a xe2x80x94CHxe2x80x94 radical, the lightening being ensured, at basic pH, using an oxidizing agent which is mixed with the composition (A) just prior to use, or which is present in a separate composition (B) that is applied simultaneously.
Another subject of the invention is multi-compartment dyeing devices or xe2x80x9ckitsxe2x80x9d, the first compartment of which contains at least one direct dye containing an optionally delocalizable quaternized nitrogen atom and a xe2x80x94Zxe2x95x90Nxe2x80x94 bond in which Z denotes a nitrogen atom or a xe2x80x94CHxe2x80x94 radical, as well as a basifying agent, and the second compartment of which contains an oxidizing agent. Another alternative xe2x80x9ckitxe2x80x9d is composed of a first compartment containing at least one direct dye as mentioned above, a second compartment containing a basifying agent and a third compartment containing an oxidizing agent.
The invention also relates to a xe2x80x9cready-to-use compositionxe2x80x9d, characterized in that it contains, in a medium which is suitable for dyeing, at least one direct dye containing an optionally delocalizable quaternized nitrogen atom and a xe2x80x94Zxe2x95x90Nxe2x80x94 bond, in which Z denotes a nitrogen atom or a xe2x80x94CHxe2x80x94 radical, an oxidizing agent and also, if necessary, a basifying agent in an amount which is sufficient to adjust the final pH to a value above 7, and preferably to a value ranging from 8.5 to 11.
However, other characteristics, aspects, subjects and advantages of the invention will emerge even more clearly on reading the description and the examples which follow.
The direct dyes containing an optionally delocalizable quaternized nitrogen atom and a xe2x80x94Zxe2x95x90Nxe2x80x94 bond, in which Z denotes a nitrogen atom or a xe2x80x94CHxe2x80x94 radical, which may be used according to the invention are preferably chosen from the compounds of formula (I) below: 
in which Z denotes a nitrogen atom or a xe2x80x94CHxe2x80x94 radical. A and B each independently denote an optionally substituted benzenic or heterocyclic aromatic group, wherein each of the aromatic groups is optionally substituted on any ring atom, including the ring atom bound to the Z or N moiety of formula (I). The aromatic groups are preferably substituted with one or more halogen atoms or with one or more radicals such as a methyl radical, a phenyl radical, an NR1R2 radical or an OR1 radical, in which R1 and R2, simultaneously or independently of each other, represent hydrogen, a C1-C8 alkyl radical, a C1-C8 hydroxyalkyl radical or a phenyl radical. X denotes an anion, preferably chloride or methyl sulphate, it being possible for the cationic charge to form an integral part of the aromatic ring or to be carried by one of its substituents.
These dyes are well known in the prior art and are described in patent applications WO-95/01772 and WO-95/15144, the disclosures of which are incorporated herein by reference. The most important cationic dyes include basic Yellow 57, Basic Red 76, Basic Brown 16,and Basic Brown 17.
Among the compounds of formula (I) which can be used in the context of the present invention, and whose cationic charge is carried by a substituent on one of the aromatic rings, it is preferred to use the compounds of the following formulae: 
i.e., 4-aminophenylazo-2-hydroxy-8-trimethylammonio-naphthalene chloride; 
i.e., 2-methoxyphenylaze-2-hydroxy-8-trimethylammonionaphthalene chloride; 
i.e., 4-amino-3-nitrophenylazo-2-hydroxy-8-trimethylammonio-naphthalene chloride; and 
i.e., 8-trimethylammoniophenylazo-N-phenyl-3methyl-5-hydroxy-pyridazine chloride.
According to the present invention, it is even more preferred to use compounds of formula (I) whose cationic charge forms an integral part of one of the aromatic rings. Among the compounds that may be mentioned, by way of non-limiting examples, are the compounds of the following formulae: 
i.e., (1-methyl-1-phenyl)-2 (1-methine-4N-methylpyrdinylium] hydrazine chloride; 
i.e. (1-methyl-1-paramethoxyphenyl)-2-(1-methine-4N-methylpyridinylium) hydrazine chloride; 
i.e. (1-methyl-1-paramethoxyphenyl)-2-(1-methine-4N-methylpyridinylium) hydrazine methylsulphate; 
i.e., 4-dimethylaminophenylazo-2N-methyl-5N-methyl-imidazolylium chloride 
i.e., 4-dimethylaminophenylazo-2N-methyl-3N-methyl-imidazolyium chloride; 
i.e., 1-methylaminophenylazo-2N-methyl-5N-methyl-imidazolylium chloride; 
i.e., 4-aminophenylaze-2N-methyl-5N-methylimidazolylium chloride; 
i.e., 4-dimethylaminophenylazo-4N-methyl-pyridinylium chloride; and 
i.e., 4-dimethylaminophenylazo-4N-oxido-pyridinylium chloride.
The concentration of direct dye(s) of formula (I) preferably ranges from 0.001 to 5% by weight approximately relative to the total weight of the dye composition before it is mixed with the oxidizing agent, and more preferably ranges from approximately 0.05 to 2%.
The oxidizing agent is preferably chosen from hydrogen peroxide, urea peroxide, alkali metal bromates and persalts such as perborates and persulphates. The use of hydrogen peroxide is particularly preferred.
The pH of composition (A) which contains at least one direct dye of formula (I) as well as that of composition (B) containing the oxidizing agent as defined above are such that after mixing composition (A) with composition (B), the pH of the composition applied to the human keratin fibers is preferably above 7, and more preferably ranges from 8.5 to 11. The pH is preferably adjusted to the chosen value using basifying agents, or possibly acidifying agents, which are well known in the state of the art in the dyeing of keratin fibers.
Basifying agents which may be mentioned are aqueous ammonia, alkaline carbonates, alkanolamines, for example mono-, di- and triethanolamines and derivatives thereof, sodium hydroxide, potassium hydroxide and compounds of formula (II): 
in which R is a propylene residue optionally substituted with a hydroxyl group of a C1-C4 alkyl radical, R3, R4, R5, and R6, simultaneously or independently of each other, represent a hydrogen atom, a C1-C4 alkyl radical or a C1xe2x80x94C4 hydroxyalkyl radical.
The acidifying agents are conventionally inorganic acids such as, for example, hydrochloric acid, tartaric acid, citric acid and phosphoric acid.
The oxidizing composition (B) preferably comprises an aqueous hydrogen peroxide solution whose titre may range, more particularly, from 5 to 40 volumes approximately.
The basifying agent is preferably chosen from alkanolamines when moderate lightening is required, and it is more particularly represented by aqueous ammonia when more pronounced lightening is desired.
The medium suitable for dyeing is preferably an aqueous medium comprising water and more-preferably a water/solvent(s) mixture, the solvent(s) being chosen from organic solvents such as 2-butoxyethanol or ethanol.
According to a preferred embodiment of the dyeing process of the invention, the dye composition (A) described above containing a basifying agent, and more particularly an aqueous solution of ammonia or of alkanolamine described above, is mixed, at the time of use, with an oxidizing solution in an amount which is sufficient to give rise to lightening of the melanin. The mixture obtained is then applied to human keratin fibers and is left standing on them preferably for 1 to 45 minutes, more preferably for 4 to 20 minutes, after which the fibers are rinsed, optionally washed with shampoo, rinsed again and dried.
The dye compositions according to the invention also contain, in their preferred embodiments, surfactants which are well known in the art, in proportions ranging from approximately 0.5 to 55% by weight, and preferably from 2 to 50% by weight relative to the total weight of the composition, organic solvents, in proportions ranging from approximately 1 to 40% by weight, and in particular from 5 to 30% by weight relative to the total weight of the composition, or any other cosmetically acceptable adjuvant known in the prior art in the oxidation dyeing of hair.
The composition applied to the hair may be in various forms, such as in liquid, cream or gel form, or in any other form which is suitable for dyeing keratin fibers, and in particular human hair. In particular, it may be packaged under pressure in an aerosol can in the presence of a propellant and may form a foam.
Concrete examples illustrating the invention will now be given. These examples are not intended to limit the subject matter of the invention.